1. Field of the Invention
The present invention relates generally to an image forming apparatus for reading image information on an original sheet, and forming and recording an image on a record medium such as a sheet of paper and, more particularly, to an image forming apparatus for forming and recording the image based on an electronic photographic recording system.
2. Related Background Art
As an example of this type of conventional image forming apparatus, a facsimile apparatus in which a recording portion for forming and recording the image is constructed as a laser beam printer based on the electronic photographic system, is known as U.S. patent application Ser. No. 08/812,496 now U.S. Pat. No. 5,790,932, and a construction thereof will be explained with reference to FIG. 19.
Referring to FIG. 19, an image reading portion 3 for reading the image information on the original sheet is provided in an upper portion of an apparatus body on the side of its front surface. A recording portion 4 for forming and recording the image is provided in rear of the image reading portion 3.
To start with, a construction of the recording portion 4 is explained. In the recording portion 4, an uppermost sheet among record sheets P stacked in a cassette portion 50 is fed by a pick-up roller 51 and sent to an image forming portion 10 by a carry roller 26. A laser scanner 9 is disposed upwardly of the image forming portion 10, and a fixing portion 11 is disposed closer to the front surface side of the apparatus body than the image forming portion 10. Based on an image signal, the laser scanner 9 scans the surface of a photosensitive drum 10a of the image forming portion 10 by its laser beams serving as scan beams. Before this scan, the surface of the photosensitive drum 10a is uniformly charged by a primary charger 10b and then irradiated with the scan beams from the laser scanner 9, thereby forming a static latent image thereon. The latent image becomes a visible image as a toner image when toners supplied from a developing roller 10c are adhered to the latent image. Further, the toner image is transferred onto the record sheet P by a transfer charger 10f and thereafter fixed by a fixing portion 11.
After being fixed, the record sheet P, though discharged, must be discharged so that a record content can be confirmed with a recording surface directed upward, which is a so-called face-up sheet discharge. In the case of this sheet discharge, the sheets are discharged on a sheet discharge cover 53 by a pair of sheet discharge rollers 11a. Further, in the case of a so-called face-down sheet discharge in which the sheets are discharged with the recording faces directed downward so as to set the output pages in sequence, the sheets are discharged on a face-down sheet discharge portion 52 by the pair of sheet discharge rollers 11a, 11b. Note that the face-up and face-down sheet discharge modes are selected by switching a flapper 14.
Next, a construction of the image reading portion 3 is described. In the image reading portion 3, original sheets S placed on an original sheet placing board 54 are singly separated by a separation roller 19 in combination with a friction piece 18 and carried to a close-fitted image sensor 7 by a sheet feed roller 21 and a sheet feed roller 22. Then, the image information on the original sheets S are read, and thereafter the sheets are discharged on an original sheet discharge tray 8 by a sheet discharge roller 23 and a sheet discharge roller 24.
Further, the image reading portion 3 is rotatable from the illustrated position about a fulcrum B counterclockwise in the Figure, and a face-down sheet discharge guide 15 is rotatable counterclockwise about a fulcrum C. The original sheet placing board 54 and the face-down sheet discharge portion 52 are integrally constructed as a cartridge cover 55, and this cover 55 is rotatable clockwise about a fulcrum D.
When replacing a toner cartridge 10e constructed integrally with the photosensitive drum 10a, the charger 10b, the developing roller 10c and a toner storing portion, the cartridge cover 55 is opened by rotating clockwise this cover 55, thus replacing the toner cartridge 102. Further, if a record sheet jam occurs, the image reading portion 3 is rotated counterclockwise, and next the face-down sheet discharge guide 15 is rotated counterclockwise, and the jammed record sheets are taken out.
There arise, however, the following defects inherent in the prior art apparatus.
First, because of such a structure that the toner cartridge 10e is, when replaced, taken out and in from above by opening the cartridge cover 55, it is required that an area of the cover 55 which covers the image forming portion 10 be larger than at least a projection area of the toner cartridge 10e. It is also required that a size thereof be set with some allowance so that the hands of an operator does not touch on the apparatus when taking out and in the toner cartridge. Then, a large dead space might be formed at an upper central portion of the apparatus body in order to make the large cover 55 rotatable clockwise in FIG. 19 so as not to impinge upon the image reading portion 3. Accordingly, this might hinder downsizing of the apparatus.
Second, in the construction given above, if the record sheets are jammed, the image reading portion 3 is rotated counterclockwise, and next the face-down sheet discharge guide 15 is rotated counterclockwise, thus taking out the jammed record sheets. This structure has such an inconvenience that both of the image reading portion 3 and the face-down sheet discharge guide 15 must be always opened when executing the jam treatment.